"I don't need the full capabilities of OCI." In my (now very much stagnating) Nix-like pet project[1] I merely want a hermetic build environment. Rolling my own container runtime was no more difficult than, what would likely be, a nightmare of emulating a complete OCI container for the simple purpose that I'm after.

Simple problems need simple solutions, and OCI is really complex. I was initially overjoyed by the prospect of deleting my code, but it looks like this project doesn't have rootless/shadowutils support yet (which is solely useful for not having to worry about su or caps during development).

[1]: https://github.com/porkg/porkg/tree/rs